JPH0882951A - Toner for developing electrostatic charge image and image forming method - Google Patents

Abstract

PURPOSE: To provide an image forming method by which satisfactory image quality and fixability are ensured even in a high-speed copying machine and offsetting is not caused. CONSTITUTION: A toner consisting of at least a bonding resin, a colorant and a releasing agent, having 6.0-9.0μm vol. average particle diameter and contg. 10-40 number% particles each having <=5μm particle diameter and 0-20 number% particles each having <=4μm particle diameter is fixed by a fixing means with a means of separately controlling the temps. of two fixing rolls having 95-100 deg. and 60-80 deg. rubber hardness, respectively, at 310-550mm/sec fixing line speed under 2.7-5.4kg/cm<2> fixing load. At this time, the toner is fixed under conditions satisfying 260 deg.C<=Ta+Tb, |Ta-Tb|<=100 deg.C and Ta>=Tsp (where Ta is the temp. of one of the rolls, Tb is the temp. of the other and Tsp is the softening point of the toner).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer and an image forming method in an electrophotographic image forming method.

[0002]

2. Description of the Related Art In an electrostatic charge image developing method such as an electrophotographic method, it is usually obtained by charging a latent image carrier, exposing it to form an electrostatic latent image, and developing the electrostatic latent image with toner. The transferred toner image is transferred to a support such as transfer paper. This is fixed and a fixed visible image is obtained to complete the image formation.

Many studies have been made for some time on the technical problems in each of these processes. One of the recent technical problems is to improve the fixability of fine powder toner, which is required for improving image quality. Further, high-speed fixing property, retention of temperature of heat roller in continuous copying for a long time, curl phenomenon of support paper, prevention of paper jam, and reduction of warm-up time are required.

However, the fine powder toner for high image quality is not sufficiently fixed as compared with the conventional toner, so that it has been postponed to be adopted in the high speed copying machine.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner and an image forming method for obtaining sufficient image quality and fixability even in a high speed copying machine. Another object of the present invention is to provide an image forming method which has good image quality and fixability and is free from curl and offset.

[0006]

The object of the present invention is achieved by adopting any one of the following constitutions [1] to [5].

[1] At least a binder resin, a colorant, and a release agent, having a volume average particle size of 6.0 to 9.0 μm, 10 to 40% by number of particles of 5 μm or less, and 4 μm or less of particles. It has means for independently controlling the temperature of two fixing rollers of 0 to 20% by number of toners (a) roller having a rubber hardness of 95 to 100 ° and (b) roller having a rubber hardness of 60 to 80 °. , A fixing load of 2.7 to 5.4 kg / cm ² , and a fixing line speed of 310 to 550 mm / sec. (A)
An image forming method characterized in that the fixing is carried out under the condition that the roller temperature Ta, (b) the roller temperature Tb, and the toner softening point Tsp satisfy the following ranges.

260 ° C. ≦ Ta + Tb, | Ta−Tb | ≦ 100 ° C., Ta ≧ Tsp [2] (a) Critical surface tension γca of roller surface,
(B) Critical surface tension γcb of roller surface, (a) Surface tension γo of oil applied to roller or (b) roller
However, the image forming method according to [1] is characterized in that the fixing is carried out under the condition satisfying the following range.

0 ≦ γo−γca ≦ 16 0 ≦ γo−γcb ≦ 1
6 [3] It is characterized in that the foamed silicone rubber layer is formed on the cored bar on the roller (a) or the roller (b), and the roller having the polyester layer formed on the foamed silicone rubber layer is contacted for cleaning. The image forming method according to [1].

[4] In the image forming method described in [1], the binder resin of the electrostatic image developing toner is polyester having an acid value of 28 to 56 and a chloroform insoluble content of 3 to 22% by weight. Toner to use.

[5] Used in the image forming method according to [1], wherein the releasing agent contained in the toner for developing an electrostatic image has a melting point of 60 to 150 ° C. and a melt viscosity of 15 to 120 cs. Toner.

[0012]

The present invention will be described in more detail below.

<Fixing System> In the heat roller system of the present invention, a fluorine resin, that is, polytetrafluoroethylene, perfluoroalkyl vinyl ether, polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, and Those in which a resistance adjusting agent, an antiwear agent, etc. are dispersed and coated are preferable. A soft roller having a silicone rubber elastic body and a fluororubber latex layer provided between the aluminum tube and the surface fluororesin layer is suitable.

In general, a combination of only soft rollers cannot obtain sufficient fixing property, so that the rollers contacting the transfer surface of the transfer paper preferably have a rubber hardness of 95 to 100 °.

It is preferable that these rollers are pressed with a constant pressure, and that the load is applied by a spring from the end. The load in this case is preferably such that the surface pressure applied to the transfer paper is 2.7 to 5.4 kg / cm ² . If this load is low, sufficient heat cannot be applied during fixing. Also, when the load of fixing is high, a large load is applied to the paper, the paper is smoothed,
An image with a lot of gloss will be produced, and the quality will be deteriorated. The nip width between the upper and lower rollers in fixing is preferably 8 to 14 mm, and the speed at which the transfer paper passes through the nip portion (line speed of the fixing roller) is preferably 310 to 550 mm / sec.
The diameter of the fixing roller is not particularly limited, but a range of 50 to 70 mm is preferable in order to secure high-speed fixing property.

<Fixing Roller Temperature> The fixing roller temperature is (a) roller temperature Ta and (b) roller temperature Tb.
And the toner softening point Tsp should satisfy the following conditions.

If 260 ° C. ≦ Ta + Tb, | Ta−Tb | ≦ 100 ° C., Ta ≧ Tsp 260 ° C.> Ta + Tb or T <Tsp, the fixing ratio is insufficient and the cold offset increases rapidly. ｜ Ta-Tb ｜ ＞ 10
At 0 ° C., a difference in water content occurs between the front and back of the transfer paper, causing curling. Curl causes paper jams. Further, Ta is preferably higher than the melting point of the release agent.

<Critical Surface Tension of Fixing Roller> The critical surface tension of the fixing roller is preferably 23 dyne / cm or less, more preferably 18 dyne / cm or less in view of releasability.

The critical surface tension of the fixing roller is a value obtained by measuring the contact angle with the n-alkane and extrapolating the surface tension at which the contact angle becomes zero.

<Application of Oil to Fixing Roller> It is preferable to apply oil to the fixing roller in order to enhance releasability.

In order to further enhance the releasability, (a) the critical surface tension γca of the roller surface and (b) the critical surface tension γcb of the roller surface, (a) the surface of the oil applied to the roller or (b) the roller. It is preferable to fix under the condition of 0 ≦ γo−γca ≦ 16 and 0 ≦ γo−γcb ≦ 16 between the tensions γo.

The oil to be applied is not particularly limited, but dimethyl silicone oil, methyl-phenyl silicone oil, phenyl silicone oil, mercapto modified silicone oil, fluorosilicone oil and the like are preferably used.

Although the coating method is not particularly limited, an oil regulating member is provided on the surface of an aluminum tube having a large number of minute holes, and a silicone oil is filled in the aluminum tube to form a coating device (a). It is particularly preferable to use a roller or (b) a roller that is brought into contact with the roller and rotated by being driven or fed to apply a small amount of oil to the roller surface.

Further, the oil retaining layer wound around the surface of the core metal is impregnated with silicone oil and brought into contact with the roller (a) or the roller (b) by capillary action and rotated by being driven or fed to rotate the roller surface. Coated with a small amount of oil on the web, or a web made by impregnating heat-resistant non-woven paper with silicone oil (a) roller,
Alternatively, (b) a roller which is brought into contact with a roller to apply a small amount of oil, a heat-resistant non-woven fabric or a heat-resistant brush is impregnated with silicone oil, and (a) a roller or (b) is brought into contact with the roller and rotated by being driven or fed. It is preferable to use a roller to apply a small amount of oil to the roller surface. The coating amount is preferably 0.04 to 2.0 mg, and more preferably 0.1 to 0.8 mg per A4 paper for one fixing.

In order to sufficiently hold the oil in the coating means, the oil viscosity is 1,000 to 50,000 cs at 20 ° C., preferably
It is 5,000-30,000cs. If the oil viscosity is lower than this range, image defects such as stains due to oil on the transfer paper occur. If the oil viscosity is higher than this range, sufficient releasability cannot be exhibited.

<Cleaning Method for Fixing Roller> It is preferable that the fixing roller has a cleaning means.

In a preferred embodiment, a foamed silicone resin layer is provided on the surface of the core metal, a polyester resin layer is provided on the silicone resin layer, and the roller is contacted with a roller (a) or a roller (b) and driven or rotated. By doing so, the roller surface is cleaned. In order to improve the cleaning property, the polyester resin having the same composition as the binder resin of the toner is particularly preferably used.

<Electrostatic charge developing toner> The toner contains a binder resin, a colorant, a releasing agent and other additives which are optionally used. In the present invention, the image quality is improved. Therefore, the average particle size is 6-9μ in terms of volume average particle size.
m, preferably 7.5 to 8.5 μm. In order to secure the life of the developer, particles of 5 μm or less are contained in an amount of 10 to 40% by number,
A toner having 0 to 20% by number of particles having a size of μm or less is used.

The binder resin of the present invention may be a resin usually used as a toner binder resin, such as styrene / acrylic resin, polyester resin, poreimide resin or epoxy resin. A polyester resin is preferably used because of its fixability at low temperature. Particularly preferably, a polyester obtained by polycondensing a monomer composition containing the following components T1, T2 and T3 is used.

Component T1; Trivalent or higher polyvalent monomer Component T2; Aromatic dicarboxylic acid component T3; Aliphatic dialcohol The trivalent or higher polyvalent monomer which is the component T1 is, for example, 1,2. , 4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid,
2,5,7-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4, -butanetricarboxylic acid, 1,2,5-
Hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxy) methane, 1,2,7,8-octanetetracarboxylic acid, enpol trimer acid, and these Examples thereof include acid anhydrides and esters.

Among these trivalent or higher polyvalent monomers, in the polyester using the aliphatic dialcohol according to the present invention, aromatic polycarboxylic acids are particularly preferable, and further benzenetricarboxylic acid and these acids are used. Benzenetricarboxylic acids such as anhydrides or esters can impart stable triboelectric charging properties.

That is, since the polyester using the aliphatic dialcohol has overwhelmingly less π electrons as compared with the polyester using the conventional bisphenol alcohol,
Although the rise rate of charge tends to decrease, it is thought that this can be prevented by selecting benzenetricarboxylic acids, anhydrides or esters of these acids, etc. as polyvalent monomers having a valence of 3 or more. To be

The compounding ratio of the trivalent or higher polyvalent monomer is preferably 1 to 30 mol% of the total monomer composition. When polyester in this range is used, release of the release agent can be further prevented.
The reason is that the polyester in this range has good compatibility with a release agent having a low molecular weight, and therefore the dispersion of the release agent in the resin is fine and uniform, and the adhesive strength with the resin is improved. Is. More preferably 1 of the total monomer composition
~ 15 mol%.

Examples of the aromatic dicarboxylic acid as the component T2 include phthalic acid, isophthalic acid, terephthalic acid, anhydrides or esters of these acids, and the like.

Other dicarboxylic acids may be used in combination with the above aromatic dicarboxylic acids. Such other dicarboxylic acids include, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, cyclohexanedicarboxylic acid, succinic acid, adibic acid, sebacic acid, malonic acid, or anhydrides of these acids. Alternatively, a lower alkyl ester, a dimer of linoleic acid, or another bifunctional organic acid monomer can be used. The mixing ratio of such other dicarboxylic acid is preferably 30 mol% or less based on the whole dicarboxylic acid. When the blending ratio of the other dicarboxylic acid is excessively large, the glass transition point Tg of the specific polyester is lowered and white spots are likely to occur in the solid portion.

As the aliphatic dialcohol as the component T3, an aliphatic dialcohol having 2 to 10 carbon atoms is preferable in order to further improve the dispersion of the release agent.

Specific examples of the aliphatic dialcohol include 1) branched chain aliphatic dialcohols: propylene glycol (1,2-propanediol) 1,2-butanediol 1,3-butanediol 2 , 3-Butanediol Neopentyl glycol 3-methylpentane-1,3,5-triol 1,2-hexanediol 2,5-hexanediol 2-methyl-2,4-pentanediol 3-methyl-1,5- Pentanediol 2-ethyl-1,3-hexanediol 2) As an aliphatic dialcohol having no branched chain, ethylene glycol 1,3-propanediol 1,4-butanediol diethylene glycol 2-butene-1,4- Diol 1,5-pentanediol 1,6-hexanediol dipropylene glycol triethylene glycol tetraethylene glycol tripropylene glycol, etc. .

Other dialcohols may be used in combination with the above aliphatic dialcohols. Examples of such other dialcohols include 1,4-bis (hydroxymethyl)
Other bifunctional alcohol monomers such as cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and etherified bisphenols such as polyoxypropylene bisphenol A can be used. The blending ratio of such other dialcohol is preferably 30 mol% or less of the total dialcohol.

<Acid Value> The acid value of the binder resin is preferably 28 to 56. When the acid value decreases, the adhesiveness between the transfer paper and the toner decreases, and as a result, the fixing rate decreases. When the acid value is too high, the hygroscopicity of the toner increases, and the charge amount tends to decrease in a high temperature and high humidity environment. Here, the acid value (AV) is 1 g of the sample.
It refers to the number of milligrams of potassium hydroxide necessary to neutralize the acid contained therein. The hydroxyl value (OHV) is
It refers to the number of milligrams of potassium hydroxide necessary to neutralize acetic acid bound to a hydroxyl group when 1 g of a sample is acetylated according to the standard oil and fat analysis test method (edited by Japan Oil and Fat Chemistry Association).

In polyester, the sum of AV and OHV means the number of end groups of the polymer molecular chain, and this value has a great influence on the release of the release agent.

<Chloroform-insoluble matter> Chloroform-insoluble matter is preferably 3 to 22% by weight for preventing offset.

Here, the chloroform insoluble matter means a filter paper impermeable matter when a sample is dissolved in chloroform, and can be obtained as follows.

The resin sample was finely pulverized, and 5.00 g of the sample powder that passed through a 40-mesh sieve was collected and placed in a container having a capacity of 150 ml together with 5.00 g of the filter aid Radiolite (+700), and 100 g of chloroform was placed in this container. Is added, placed on a ball mill stand and rotated for 5 hours or more to sufficiently dissolve the sample in chloroform. Meanwhile, the pressure filter has a diameter of 7 cm.
Filter paper (No. 2) was placed on it, 5.00 g of radiolite was uniformly precoated on it, and a small amount of chloroform was added to bring the filter paper into close contact with the filter, and then the contents of the container were filtered. Pour into. Further, the container is thoroughly washed with 100 ml of chloroform and poured into a filter so that no deposits remain on the container wall. After that, the upper lid of the filter is closed and filtration is performed. Filtration is performed under a pressure of 4 kg / cm ² or less, and after the outflow of chloroform is stopped, 100 ml of chloroform is newly added to wash the residue on the filter paper, and pressure filtration is performed again.

After the above operation was completed, all of the filter paper, the residue on it, and the radiolite were placed on an aluminum foil and placed in a vacuum dryer, and the temperature was 80 to 100 ° C and the pressure was 100 mm.
It was dried under Hg condition for 10 hours, and the total weight a (g) of the dry solid thus obtained was measured. Chloroform insoluble matter x
(% By weight) is calculated.

The chloroform-insoluble matter thus obtained is a high molecular weight polymer component or a crosslinked polymer component in the polyester resin. Chloroform-insoluble matter as described above, in the polymerization reaction of alcohol and carboxylic acid, by appropriately selecting the reaction conditions,
Alternatively, by forming a suitable crosslinking agent in the reaction system, it can be formed at a considerably controlled rate.

<Release Agent> A release agent having a melting point of 60 to 150 ° C. and a melt viscosity of 15 to 120 cs is preferably used for preventing offset.

As the releasing agent, for example, waxes such as paraffin wax, sazol wax, fatty acid ester, partially saponified fatty acid ester, polyhydric alcohol ester, and mixtures thereof can be used. An amide wax may be used together. Among these, ester waxes containing an ester group are preferable because they have good compatibility with the polyester resin.

As the fatty acid ester, for example, maleic acid ethyl ester, maleic acid butyl ester, stearic acid methyl ester, stearic acid butyl ester, palmitic acid cetyl ester, montanic acid ethylene glycol ester and the like can be used.

As the partially saponified fatty acid ester, for example, a partially saponified product of calcium of montanic acid ester can be used. Of these fatty acid esters, carnauba wax is particularly preferable.

As the polyhydric alcohol ester, for example, glycerin stearate, glycerin ricinolate, glycerin monobehenate, sorbitan monostearate, propylene glycol monostearate, sorbitan trioleate and the like can be used.

In order to improve the dispersion of the low melting point ester wax, it is preferable to use an amide wax together.

As the amide wax, for example, stearic acid amide, oleic acid amide, palmitic acid amide, lauric acid amide, behenic acid amide, methylenebisstearamide, ethylenebisstearamide, etc. can be used.

The melting point was measured by placing a small amount of a sample in a glass capillary tube, placing it in a sulfuric acid bath, heating it, and visually observing the point where it melted transparently. The bath temperature at that time was taken as the melting point.

The mixing ratio of the releasing agent is 100% by weight of the binder resin 100.
The amount is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. When the compounding ratio of the release agent is too small, the offset resistance and wrapping resistance of the toner deteriorate, while when it is too large, streaky dispersion tends to occur.

<Toner Softening Point> The toner softening point Tsp is preferably 115 to 140 ° C., more preferably 120 to 135 ° C.

Here, the softening point Tsp is measured by using a Koka type flow tester "CFT-500 type" (manufactured by Shimadzu Corporation) after allowing the toner or the binder resin to stand at 20 ° C and 50% relative humidity for 2 hours. The conditions are load 20 kg / cm ² , nozzle diameter 1 mm,
Nozzle length 1 mm, preheating at 80 ° C for 10 minutes, heating rate 6
When measured and recorded as a sample amount of 1 cm ³ (weight expressed by true specific gravity × 1 cm ³ ) at ° C / min, the height of the S-shaped curve in the plunger drop amount-temperature curve (softening flow curve) of the flow tester is h When, it means the height of h / 2.

<Colorant> The colorant forming the colored particles (toner) is not particularly limited, and various conventionally known materials can be used. Examples thereof include carbon black, nigrosine dye, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and rose bengal.

<Other Additives> As other additives, for example, a charge control agent such as salicylic acid derivative / azo metal complex, and in the case of obtaining a magnetic toner, colored particles contain magnetic particles as an additive. It As the magnetic particles, particles such as ferrite magnetite having an average primary particle diameter of 0.1 to 2.0 μm are used. The amount of the magnetic particles added is 20 to 70% by weight of the colored particles.

From the viewpoint of imparting fluidity, fine inorganic particles may be added to the colored particles. As the inorganic fine particles, inorganic oxide particles such as silica, titania, and alumina are preferable, and further, these inorganic fine particles are preferably hydrophobized with a silane coupling agent, a titanium coupling agent, or the like.

<Carrier> The two-component developer according to the present invention is used by mixing the toner of the present invention with a known carrier.

The carrier is magnetic particles having a volume average particle diameter of 5 to 200 μm, or a resin-coated carrier having the magnetic particles as a core material and coated with a resin, or a volume average particle diameter of 0.1 to 1
A resin dispersion type carrier in which magnetic particles of μm are dispersed in a binder resin is used.

[0062]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following description, "part" means "part by weight".

<Production of Binder Resin for Toner> Neopentyl Glycol 132 parts Ethylene glycol 60 parts Terephthalic acid 279 parts Dibutyltin laurate 1.5 parts The above sample was thermometer, stainless steel stirring rod, glass nitrogen introducing pipe, Then, put it in a container equipped with a flow-down type condenser, and at the time when no change is observed in the softening point value according to ASTM E28-51T at 170 ° C under normal pressure in a mantle heater under nitrogen atmosphere, 1,2,4- 108 g of benzenetricarboxylic anhydride was added, the reaction was continued at 210 ° C., the progress of the reaction was traced from the softening point according to ASTM E28-51T, and the reaction was stopped when the softening point reached a predetermined temperature, After cooling to room temperature, a binder resin "R-1" was obtained. The binder resin "R-1" had an acid value of 51 and a chloroform insoluble content of 15% by weight.

<Manufacture of Toner> Binder resin: R-1 100 parts by weight Colorant: Mogar L (manufactured by Cabot) 10 parts by weight Release agent: Main component is fatty acid ester (alcohol having 32 carbon atoms and 24 carbon atoms) (Fatty acid ester composed of fatty acids of 2) (melting point 84 ° C, melt viscosity 20cs) 2 parts by weight; Henschel mixer kneading; twin-screw kneading extruder 170 ° C coarse crushing; hammer mill crushing; jet crusher Classification: Air classifier Colored particles having a volume average particle size of 8.0 μm were obtained as described above. 100 parts by weight of the colored particles and 1.0 part by weight of hydrophobic silica were mixed with a Henschel mixer to obtain a toner "T-1".

The softening point Tsp of Toner "T-1" was 122 ° C.

<Manufacture of Carrier> Core material particles (ferrite particles having an average particle size of 70 μm) 100 parts Resin particles (1,1,1-trifluoroethyl methacrylate having an average particle size of 0.1 μm) 2 parts Horizontally a carrier raw material of 2 parts or more Put into a rotary-blade mixer, heat to 90 ° C while mixing, and mix for 40 minutes.
I got 1 ".

The carrier C-1 and the toner T-1 were mixed so as to have a toner concentration of 5% by weight to prepare a developer.

Fixing (a) Roller An aluminum tube having an outer diameter of 60 mm and an inner diameter of 50 mm was subjected to a primer treatment containing iron oxide as a main component to form a silicone rubber layer having a thickness of 0.1 mm, and then a thickness of 0.03 mm. The perfluoroalkyl vinyl ether layer of was formed. The rubber hardness of the roller was 99 degrees, and the critical surface energy γca obtained by extrapolation from the contact angle of the n-alkane was 8 dyne / cm.

Fixing (b) Roller A (b) roller was obtained in the same manner as the (a) roller except that the thickness of the silicone rubber layer was 5 mm.

The rubber hardness of the roller is 65 degrees. The critical surface energy γca obtained by extrapolation from the contact angle of n-alkane is
It was 8 dyne / cm.

Commercially available electrophotographic copying machine Konica U-BIX-50
82 (manufactured by Konica Co., Ltd.) is equipped with a negatively charged organic photoreceptor on a fixing unit portion of a modified unit (a), (b) roller (a) so that the roller contacts the transfer surface of the transfer sheet.
I installed each. The width of contact between the transfer sheet and the fixing roller is 12 mm, and the fixing load applied to the transfer sheet is 2.9 kg / c.
It was adjusted with a fixing spring to be m ² . The line speed of the rollers (a) and (b) was modified to 410 mm / sec. A halogen lamp heater connected to a variable resistor as a fixing heater was installed in each of the central portions of the rollers (a) and (b), and the temperatures of the two fixing rollers were independently controlled.

The developer is toner T-1, carrier C-1.
Was mixed and used so that the toner concentration becomes 5% by weight.

Example 1 A3 size paper having a weight of 70 kg was continuously copied while forming a solid image having a relative density of 1.0 and 1.5 cm × 1.5 cm with respect to a white background, and fixing during continuous copying was performed by adjusting the electric power of a fixing heater ( a) Roller temperature Ta is 130
The temperature Tb of the fixing (b) roller was controlled to 130 ° C.

Example 2 Fixing (a) Roller Temperature Ta
Was 180 ° C. and the fixing (b) roller temperature Tb was 80 ° C., and continuous copying was performed in the same manner as in Example 1.

Example 3 Fixing (a) Roller Temperature Ta
Was 200 ° C. and the fixing (b) roller temperature Tb was 150 ° C., and continuous copying was carried out in the same manner as in Example 1.

Example 4 Fixing (a) Roller Temperature Ta
Was 200 ° C. and the temperature (Tb) of the fixing (b) roller was 100 ° C., and continuous copying was performed in the same manner as in Example 1.

Example 5 Fixing (a) Continuous as in Example 1 except that 0.4 mg / A4 of methyl silicone oil with a surface tension of 20 dyne / cm (viscosity of 30,000 cs at 20 ° C.) was applied to each roller. I copied it.

Example 6 Fixing (a) Continuous as in Example 1 except that a roller having a foamed silicone rubber layer formed on the cored bar and a polyester layer formed on the outer layer of the roller was contacted. I copied it.

Comparative Example 1 Fixing (a) Roller Temperature Ta
Was 129 ° C. and the fixing (b) roller temperature Tb was 129 ° C., and continuous copying was performed in the same manner as in Example 1.

Comparative Example 2 Fixing (a) Roller Temperature Ta
Was 181 ° C. and the fixing (b) roller temperature Tb was 79 ° C., and continuous copying was performed in the same manner as in Example 1.

Comparative Example 3 Fixing (a) Roller Temperature Ta
Was 120 ° C. and the temperature (Tb) of the fixing (b) roller was 140 ° C., and continuous copying was carried out in the same manner as in Example 1.
In this example, Ta ≧ Tsp is not satisfied.

Comparative Example 4 Fixing (a) Roller Temperature Ta
Was controlled to 180 ° C. and the fixing (b) roller temperature Tb was controlled to 78 ° C., and continuous copying was performed in the same manner as in Example 1.

<Measurement of Fixing Rate> Relative Density to White Background 1.
Form a solid image of 0, 1.5 cm x 1.5 cm, and load 2115
g, after rubbing 15 times with a weight wrapped with salashi on the surface of a metal plate having a contact area of 6.5 cm x 100 cm, the relative density to a white background was measured with a Sakuradensitometer (manufactured by Konica Corporation),
The fixing ratio was measured according to the following formula.

<Fixing rate (%)> = {<Image density after rubbing> / <Image density before rubbing>} × 100 If the fixing rate is 70% or more, the fixing strength is practically no problem.

<Transfer Sheet Curl Amount> A3 size paper having a weight of 70 kg was placed on a horizontal table immediately after copying, and the edge of the paper was represented by a length curved from a horizontal plane. If the curl amount is 20 mm or more, problems such as paper jams in the sorter part will occur.

<Measurement of Offset Amount> A solid image having a relative density of 1.3 and 7.5 cm × 22.5 cm with respect to a white background was formed at the tip of the image, and the relative density of the portion formed by offsetting the solid image was measured. If the offset amount is 0.01 or less,
There is no problem in practical use.

Table 1 shows the above evaluation results.

[0088]

[Table 1]

As described above, according to the present invention, it is possible to obtain a good image having an excellent fixing rate and no curl or offset.

[0090]

According to the present invention, it is possible to obtain sufficient image quality and fixability even in a high-speed machine, have good image quality and fixability, and have no offset or transfer paper curl and an image forming method. To be

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location G03G 9/08 365 (72) Inventor Hiroyuki Kozuru 2970 Ishikawacho, Hachioji, Tokyo Konica Stock Company ( 72) Inventor Shoichi Nakano 2970 Ishikawa-cho, Hachioji City, Tokyo Konica Stock Company

Claims (5)

[Claims] 1. A volume average particle diameter of 6.0 to 9.0 μm, which is composed of at least a binder resin, a colorant, and a release agent.
Particles of 5 μm or less 10 to 40% by number, particles of 4 μm or less are 0
To 20% by number of toner, and has means for independently controlling the temperature of two fixing rollers of (a) roller having a rubber hardness of 95 to 100 ° and (b) roller having a rubber hardness of 60 to 80 °, Fixing load 2.7 to 5.4 kg / cm ² , fixing line speed 310
(A) roller temperature Ta, (b) roller temperature Tb, and toner softening point in the fixing means at a rate of up to 550 mm / sec.
An image forming method, wherein Tsp is fixed under the condition satisfying the following range. 260 ℃ ≦ Ta + Tb, | Ta−Tb | ≦ 100 ℃, Ta ≧ Tsp 2. (a) The critical surface tension γc of the roller surface
The a, (b) critical surface tension γcb of the roller surface and the surface tension γo of the oil applied to the (a) roller or the (b) roller are fixed under conditions satisfying the following ranges: Image forming method. 0 ≦ γo−γca ≦ 16 0 ≦ γo−γcb ≦ 16 3. The roller (a) or the roller (b),
The image forming method according to claim 1, wherein a foamed silicone rubber layer is formed on the cored bar, and a roller having a polyester layer formed on the foamed silicone rubber layer is brought into contact with the core to perform cleaning. 4. A volume average particle diameter of 6.0 to 9.0 μm, which is composed of at least a binder resin, a colorant, and a release agent,
Particles of 5 μm or less 10 to 40% by number, particles of 4 μm or less are 0
To 20% by number of toner, and has means for independently controlling the temperature of two fixing rollers of (a) roller having a rubber hardness of 95 to 100 ° and (b) roller having a rubber hardness of 60 to 80 °, Fixing load 2.7 to 5.4 kg / cm ² , fixing line speed 310
(A) roller temperature Ta, (b) roller temperature Tb, and toner softening point in the fixing means at a rate of up to 550 mm / sec.
The binder resin of the electrostatic image developing toner in the image forming method in which Tsp is fixed under the condition satisfying the following range has an acid value of 28 to
56. A toner for developing an electrostatic image, which is polyester having a chloroform insoluble content of 3 to 22% by weight. 260 ℃ ≦ Ta + Tb, | Ta−Tb | ≦ 100 ℃, Ta ≧ Tsp 5. A volume average particle diameter of 6.0 to 9.0 μm, which is composed of at least a binder resin, a colorant, and a release agent.
Particles of 5 μm or less 10 to 40% by number, particles of 4 μm or less are 0
To 20% by number of toner, and has means for independently controlling the temperature of two fixing rollers of (a) roller having a rubber hardness of 95 to 100 ° and (b) roller having a rubber hardness of 60 to 80 °, Fixing load 2.7 to 5.4 kg / cm ² , fixing line speed 310
(A) roller temperature Ta, (b) roller temperature Tb, and toner softening point in the fixing means at a rate of up to 550 mm / sec.
Tsp is a toner characterized in that the melting point of the release agent contained in the toner for developing an electrostatic image in the image forming method for fixing under the conditions satisfying the following range is 60 to 150 ° C. and the melt viscosity is 15 to 120 cs. Toner for charge image development. 260 ℃ ≦ Ta + Tb, | Ta−Tb | ≦ 100 ℃, Ta ≧ Tsp